#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <numeric>
#include <functional>
#include <cmath>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <sstream>
#include <string>
#define _repargs(_1,_2,_3,name,...) name
#define _rep(i,n) repi(i,0,n)
#define repi(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define rep(...) _repargs(__VA_ARGS__,repi,_rep,)(__VA_ARGS__)
#define all(x) (x).begin(),(x).end()
#define mod 1000000007
#define inf 2000000007
#define mp make_pair
#define pb push_back
typedef long long ll;
using namespace std;
template <typename T>
inline void output(T a, int p = 0) {
    if(p) cout << fixed << setprecision(p)  << a << "\n";
    else cout << a << "\n";
}
// end of template

int main() {
    cin.tie(0);
    ios::sync_with_stdio(0);
    // source code
    
    int N;
    cin >> N;
    vector<ll> A(N);
    rep(i, N) cin >> A[i];
    vector<ll> B(N + 1);
    B[0] = 1;
    rep(i, N){
        if(i % 2 == 0) B[i + 1] = A[i] - B[i];
        else B[i + 1] = B[i + 1] = B[i] - A[i];
    }
    
    bool ok = true;
    rep(i, N + 1) if(B[i] <= 0) ok = false;
    if(ok){
        output(N + 1);
        rep(i, N + 1) output(B[i]);
    }
    else{
        output(-1);
    }
    
    
    return 0;
}